Presently, fiberboards and sheets are made utilizing stationary platen presses which operate intermittently. While generally satisfactory for thick fiberboard products, about 0.125 to 0.75 inch in thickness, such intermittent procedure is not economically practical for the manufacture of thin fiberboard products, i.e., those having a thickness of about 0.009 to 0.16 inch. The reasons for this are that intermittent type presses involve irreducible periods of time for opening and closing and as the weight per unit area of the board product decreases as its thickness is reduced, the operating costs per unit weight become prohibitively high. While continuous type presses exist, attempts to use them have not been successful for thin fiberboards since it was not possible to get the proper cure and thickness as well as strength of product with any commercially suitable dwell time in the press. Such presses require that the cure must take place in a period of seconds. Thus, the economic and commercial advantages inherent in continuous operation have thus far not been usable for the manufacture of thin fiberboards or sheets, i.e., those thinner than 0.16 inch.